To act adaptively in complex worlds, animals require the ability identify relevant information, which helps improve their predictions and reduce the uncertainty of future actions. The selection of relevant information is accomplished by systems of attention, which have been intensively investigated in the visual domain. These studies have focused on attentional modulations of sensory perception and on mechanisms of oculomotor target selection. However, less is known about the cognitive mechanisms of attentional control: how does the brain identify stimuli that are relevant or attention worthy in a given task? Evidence from computational and behavioral studies suggests that relevance depends both on the reward associations and on the informational properties of a sensory cue. However, informational properties (uncertainty, new information) are investigated mostly in studies of learning, while studies of oculomotor control focus on the role of reward. Thus it is unknown how the brain computes relevance based on both the reward and informational constraints of a task. In the oculomotor system, two areas implicated in attentional control are the frontal eye field (FEF) and the lateral intraparietal area (LIP). However, studies of these areas have focused on their role in target selection rather than computing relevance per se. In addition, these studies reveal very similar responses in FEF and LIP, raising questions regarding their specific roles. Here we aim to answer these questions by using a combination of single neuron recordings and reversible inactivation and explicitly comparing FEF and LIP. We seek to understand (1) how is target selection in FEF and LIP influenced by reliability/uncertainty and redundancy/new information, (2) how are these variables related to expected reward and (3) whether LIP/FEF have distinct contributions to discounting redundant information and attending to reliable versus uncertain cues. The studies are innovative in that they link two topics that have been pursued in isolation, the study of attention on one hand and that of learning and statistical inference on the other, and directly compare the functions of FEF and LIP. The studies have high clinical significance since attentional disturbances are strong in many psychiatric disorders including attention deficit disorder, depression and addiction. Thus, the studies will lead to an integrated theory of attentional control based on reward and uncertainty reduction, processes that are core for decision making in both health and disease. PUBLIC HEALTH RELEVANCE: The ability to attend to relevant stimuli is critical for normal decision making and is impaired in many psychiatric disorders, including attention deficit disorder, depression and addiction. Converging evidence suggests that attention is controlled jointly by reward and by the uncertainty/information a stimulus may bring, but little is known about the underlying mechanisms. In addition, it is not known what the distinct contributions of parietal and frontal areas are in attentional control. Using single neuron recordings in the monkey oculomotor system, we seek to understand how uncertainty and reward interact in controlling attention and what are the distinct contributions of the parietal and the frontal lobes